Check self.theme_option before using
Check self.theme_option before using

Fixes #493
Liangjianghao/powerline,darac/powerline,s0undt3ch/powerline,junix/powerline,lukw00/powerline,EricSB/powerline,wfscheper/powerline,prvnkumar/powerline,areteix/powerline,xfumihiro/powerline,S0lll0s/powerline,xxxhycl2010/powerline,IvanAli/powerline,DoctorJellyface/powerline,Luffin/powerline,Luffin/powerline,IvanAli/powerline,magus424/powerline,xfumihiro/powerline,cyrixhero/powerline,darac/powerline,seanfisk/powerline,xxxhycl2010/powerline,cyrixhero/powerline,firebitsbr/powerline,darac/powerline,Liangjianghao/powerline,lukw00/powerline,magus424/powerline,bartvm/powerline,russellb/powerline,russellb/powerline,xxxhycl2010/powerline,QuLogic/powerline,s0undt3ch/powerline,areteix/powerline,xfumihiro/powerline,keelerm84/powerline,prvnkumar/powerline,S0lll0s/powerline,s0undt3ch/powerline,kenrachynski/powerline,S0lll0s/powerline,IvanAli/powerline,russellb/powerline,QuLogic/powerline,areteix/powerline,Liangjianghao/powerline,EricSB/powerline,seanfisk/powerline,lukw00/powerline,bartvm/powerline,cyrixhero/powerline,bezhermoso/powerline,blindFS/powerline,seanfisk/powerline,DoctorJellyface/powerline,junix/powerline,wfscheper/powerline,kenrachynski/powerline,junix/powerline,bartvm/powerline,firebitsbr/powerline,dragon788/powerline,DoctorJellyface/powerline,magus424/powerline,wfscheper/powerline,keelerm84/powerline,dragon788/powerline,Luffin/powerline,firebitsbr/powerline,bezhermoso/powerline,blindFS/powerline,blindFS/powerline,bezhermoso/powerline,prvnkumar/powerline,QuLogic/powerline,dragon788/powerline,kenrachynski/powerline,EricSB/powerline